| Equol, a gut microbial metabolite of daidzein, has been implicated to play a major role for potential beneficial effects of isoflavones, but it is produced by only30-50%of population. The gastrointestinal microbiota plays an important role in the metabolism of isoflavones, especially the formation of equol. Once formed, equol is in general metabolically stable. Equol exhibits a wide range of biological activies; including anti-oxidant and estrogenic properties. However, the factors for equol synthesis are unknown. It was found that the structure of intestinal microbiota and inter-species transference of hydrogen is very important for the production of equol. The motivations of this study are to character the equol-producing ability and its individual variation in pigs, and to develop the nutritional strategy to enhance pig equol-producing ability by modulating the structure of intestinal microbiota and inter-species transference of hydrogen. Therefore we first compared the equol-producing ability in large white sows, and then do further analyzed wether lactulose can enhance equol-producing capacity in vitro and in vivo.1. Individual differences of equol-producing capacity and the correlation with intestinal microbiota in sowsIn this study, the individual differences of equol-producing capacity and its correlation with intestinal microbiota in large white sows were assessed. Results showed that large white sows had a61.22%coefficient of variation inter-individual difference in faecal equol production. And had a48.33%coefficient of variation individual variation in urinary equol levels. The urinary log10(equol/daidzein) values were all above-1.0. Cluster analysis of denaturing gradient gel electrophoresis (DGGE) patterns from sows’ faeces showed that faecal samples had similar equol concentrations microbial composition. The population of total bacteria, firmicutes, bacteroidetes, and methanogen-producing bacteria correlated negatively with faecal equol production. The population of total bacteria, firmicutes, bacteroidetes, methanogen-producing and sulphate-reducing bacteria correlated negatively with faecal log10(equol/daidzein). A significant positive correlation between urinary equol and daidzein production populated with methanogen was also found. This study provide the first evidence that there is a relationship between equol production and the gut interspecies H2transfer in vivo.2. Lactulose promotes equol production and changes the microbial community during in vitro fermentation of daidzein by fecal inocula of sowsIn this study, the effect of lactulose on transformation of daidzein into equol by sows’fecal microbiota was investigated. Results showed that lactulose treatment improved bacteria growth parameters and modulated the kinetics of fermentation in vitro. Lactulose significantly increased total gas production, T1/2, Tmax, and Rmax. Furthermore, lactulose altered the microflora composition; increased equol production, reduced in the population of methanogen, and increased the sulfate-reducing bacteria population during24hours of incubation. Here, we report for the first time that in a certain condition (sealing or high pressure), equol might be able to re-transformed to daidzein via a dihydrodaidzein (DHD) pathway by further metabolism using lactulose as a substrate. This study proposes that "hydrogen-producing prebiotic" might be a novel approach to promote equol production in vivo or in vitro.3. Effects of dietary daidzein and lactulose on the production of equoOl in of barrowsThe present study was performed to investigate the effects of dietary supplemention of daidzein and lactulose on the equol-producing ability of barrows.36barrows aged40days were randomly allotted to one of three treatment groups. The control (C) was fed a soybean-free diet, divided Daidzein (D) and daidzein+lactulose (D+L) were the control diet containing50mg/kg daidzein and50mg/kg daidzein with1%lactulose, respectively. After21days of treatment, samples were taken for microflora and equol-producing ability analysis. The results showed that the isobutyric acid, isovaleric acid, branched chain fatty acid (BCFA) and total volatile fatty acid (TVFA) levels in the D+L group were higher than those in the D group.PCR-DGGE analysis showed the profiles of bacteria, methanogen-producing bacteria and sulfate-reducing bacteria in the colon digesta and mucosa had also changed by D+L. In addition, the bands number of bacteria, MPB and SRB in the feces, colon digesta and mucosa was manipulated by lactulose and daidzein. The number of firmicutes, bacteroidetes, and the percentage of bacteroidetes to bacteria were higher in the D+L group than D group. However, the SRB population in the D+L group was lower than that in the D group. Furthermore, methanogen-producing bacteria and sulfate-reducing bacteria in colon digesta were reduced by daidzein or daidzien with lactulose. Moreover, equol concentrations and the ratio of equol/daidzein were significantly increased by the addition of lactulose in barrows. Taken together; our data indicated that in the presence of daizein, dietary supplementation with lactulose can improve the microflora fermentation activity of colon digesta, shift the bacteria, MPB and SRB population and profile in the feces, colon digesta and mucosa. Most importantly, lactulose significantly increased the production of equol from faidzein in the intestine.4. Effects of dietary daidzein and lactulose on the growth performance, humoral immunity and liver antioxidant status in barrowsThe purpose of this study was to explore the effects of dietary daizein and lactulose on the growth performance, humoral immunity and liver antioxidant status in barrows. Results showed that no significant difference in the feed intake, average daily weight gain, body weight, organs weight and index among three groups. However, the D+L fed pigs had lower incidence of diarrhea as compared D and C groups. Blood T and B lymphocyte proliferation was no influenced by daidzien and lactulose. However, the liver oxidative biomarkers and antioxidant enzyme activities were affected. The total carbonyl,8-OH-dG levels in the D and D+L groups were higher than those in the C group. The NO and protein carbonyl concentrations were significantly lower in D group compared to those in the C group. The T-SOD and CuZn-SOD enzyme activities in D+L group were significantly higher as compared with the D and C groups. There were no differences in the levels of CAT, MDA, GSH-pX, GR, GSG, GSSG and the ratio of GSH/GSSG among three groups. Overall, daidzein can suppress the liver oxidative biomarkers, and lactulose had no addition effect on these parameters, but lactulose was found would improve the antioxidant enzymes of activities stimulated by daidzein in the liver of barrows.5. Effect of dietary daidzein and lactulose on humoral immunity and liver antioxidant status in barrows after LPS challengeIn this chapter, the effects of dietary daidzein and lactulose on humoral immunity and liver antioxidant status were studied.36barrows at40days old were randomly divided to one of three treatment groups. The control (C) barrows were fed a soybean-free control diet. Daidzein (D) and daidzein+lactulose (D+L) groups were fed the control diet containing with50mg/kg daidzein and50mg/kg daidzein with1%lactulose, respectively. After23days of treatment, half of pigs were intrapenearally injected with LPS (25μg/kg BW). The blood samples were then taken for lymphocyte proliferation after24hours of LPS induction.48hours later, animal were killed and the blood and liver samples were taken for analysis. Results showed that after LPS induction, daidzein increased T and B lymphocyte proliferation, and lactulose further enhanced cell proliferation. Plasma IL-6levels in the C group were significantly higher than the D and D+L groups. The plasma cortisol levels in the D and D+L groups was higher than those in the C group. Total carbonyl, NO,8-OH-dG, and MDA levels in the liver were reduced by daidzein treatment, but addition of fed animals further effected on these parameters. Moreover, D group had lower T-SOD, CuZn-SOD, Mn-SOD and GR enzyme activities as compared to the C group, but the lactulose+daidzein had higher T-SOD, Mn-SOD and GR activities than those in D group. These results suggest that dietary daidzein significantly modulated the humoral immunity and reduced oxidant biomarkers and anti-oxidant enzymes activity; and supplementation of lactulose can improve the humoral immunity and augment daidezin-induced antioxidant enzymes activity. |
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